Berlin – September 10, 2026 -- German environmental group Deutsche Umwelthilfe (DUH) has accused auto parts retailers and workshop chains of selling substandard replacement catalytic converters that leave up to 2.7 million gasoline vehicles with insufficient exhaust cleaning.
Lab tests find near-zero precious metal coating in five new replacement converters
Laboratory analysis commissioned by DUH on five new aftermarket catalytic converters found precious metal content approaching zero in nearly all units tested, undermining the long-term effectiveness of exhaust cleaning. Citing data from Germany's Federal Highway Research Institute (BASt), DUH said the majority of the roughly 300,000 replacement catalytic converters sold annually in Germany are substandard, prompting its conservative estimate of up to 2.7 million affected gasoline vehicles.
Survey of 21 dealers and workshop chains exposes labeling gaps
DUH surveyed 21 parts retailers, wholesalers and workshop chains on product quality. Nearly half did not respond, only two companies provided complete data, and two gave partial answers; the remainder pointed generically to ECE type approvals, established brands or their suppliers. DUH said its lab tests show converters can carry ECE certification despite containing only a fraction of the precious metal required for effective, durable emissions control, creating a competitive disadvantage for manufacturers that comply with adequate metal loading.
DUH demands OEM parts or "Blue Angel" certification as minimum standard
The organization is calling on workshops and parts dealers to install only original catalytic converters with proven cleaning performance or units certified with Germany's "Blue Angel" eco-label, available since 2013. DUH is also pressing the federal transport ministry to conduct official verification of the actual cleaning performance of replacement converters sold and installed in Germany, and to tighten requirements for periodic emissions inspections, including mandatory nitrogen oxide measurements for gasoline vehicles.
DUH plans test purchases and threatens legal action against violators
DUH said it will conduct test visits to workshop chains, measuring converters both new and after a period of use to demonstrate shortfalls in sustained cleaning performance. Jürgen Resch, DUH's federal executive director, said the Federal Motor Transport Authority (Kraftfahrt-Bundesamt) has failed in its oversight duties despite awareness of the problem. Citing planned reforms to environmental criminal law, DUH said it will pursue legal action against retailers and workshops found to knowingly sell or install ineffective converters, treating such conduct as a criminal rather than purely regulatory violation.
Earlier DUH tests found even higher-grade converters breached NOx limits eightfold
DUH previously tested catalytic converters in 2015 and measured real-world emissions from five units in 2019. Even though the precious metal content in those earlier tests was roughly double current levels, nitrogen oxide emissions exceeded legal limits by up to eight times. DUH said the substantially lower metal content found in its latest tests points to even higher real-world emissions today.